Strategies of prior art methods of production of 4,1′,6′ trichlorogalactosucrose (TGS) predominantly involve chlorination of sucrose-6-ester by use of Vilsmeier-Haack reagent derived from various chlorinating agents such as phosphorus oxychloride, oxalyl chloride, phosphorus pentachloride etc, and a tertiary amide such as dimethyl formamide (DMF) leading to preparation of TGS-6-ester. After the said chlorination reaction, the reaction mass is neutralized to pH 7.0-7.5 using appropriate alkali hydroxides of calcium, sodium, etc. to deacetylate the TGS-6-acetate to form 4,1′,6′ trichlorogalactosucrose.
Conventionally, the purification methods describe firstly the removal of the tertiary amide, usually dimethylformamide (DMF) from the chlorination reaction mixture before proceeding for extractive purification of the desired TGS. Removal of the DMF, from chlorination reaction mixture has been achieved so far by steam stripping (Navia et al 5530106, 5498709) and by drying the entire Process Stream by a method of drying under mild conditions including drying by Agitated Thin Film Dryer, spray drying and the like. There was, however, a need of a more efficient process than the above ones more suitable for industrial production.